The digital interface is a data transmitting means in a recording/reproducing apparatus such as VCR. Among said recording/reproducing apparatuses is a consumer-use digital VCR which records/reproduces high-efficiency encoded video data and non-compression voice data stored in a compact cassette, called the DV Format. The DV Format is described in the consumer-use VCR specifications introduced by The HD Digital VCR Conference (Data Compression and Digital Modulation, The Consumer-use Digital VCR;--consolidating, as a first step, the existing specifications of TV signals", pages 137-150, NIKKEI ELECTRONICS BOOKS). Also there is a report available on the digital interface of the DV Format (Digital Interface for Digital VCR", VIR95 - 56, Technical Report of The Institute of Television Engineers of Japan), which refers to the transmission of compressed video data and interleaved audio data in the DV Format using the IEEE1394 (hereinafter referred to as 1394). The format for transmitting digital data using the 1394 is called AV Protocol; in the digital VCR specifications, video data and audio data etc. on a tape are transmitted as the line of 80-byte block data called DIF block. In a case of the 525 scanning line/60 field" (hereinafter referred to as 525/60 system) signal, for example, 150 DIF blocks form 1 DIF sequence, 10 DIF sequences form 1 video frame, as shown in FIG. 10. In the following, a conventional digital interface for connecting a DV Format VCR with an outside equipment is described.
FIG. 11 is a block diagram of a conventional recording apparatus, which diagram shows the structure of a digital VCR using the 1394 digital interface. In FIG. 11, numeral 1 denotes an input terminal of the 1394 digital interface signal, 2 is a digital interface circuit (hereinafter referred to as digital I/F) for converting the 1394 Format data into bus data of certain specific units of audio data and video data (hereinafter referred to as DV bus data), 3 is a DV bus data, 4 is an error correction encoder for adding an error correction parity, 5 is a record modulator doing modulation, 6 is a record amplifier, 7 is a magnetic tape.
FIG. 12 is a block diagram of a conventional reproducing apparatus, which diagram shows the structure of a digital VCR using the 1394 digital interface. In FIG. 12, numeral 11 denotes a magnetic tape, 12 is a reproduction amplifier, 13 is a reproduction demodulator which performs equalizing, detecting and demodulating processes, 14 is an error correction decoder which performs error correction process based on an error correction parity added at recording, 15 is a DV bus data, 16 is a digital I/F which converts DV bus data into the 1394 Format data, 17 is an output terminal of the 1394 digital interface signal.
A 1394 Format digital signal delivered to terminal 1 is converted by the digital I/F 2, and generates DV bus data 3. The error correction encoder 4 adds an error correction parity to the DV bus data 3, the record modulator 5 performs modulation process for recording, and the data is recorded in the magnetic tape 7 via record amplifier 6.
When reproducing a data recorded in magnetic tape 11, a reproduced data is delivered to reproduction demodulator 13 via reproduction amplifier 12. The reproduction demodulator 13 distinguishes the 0, 1 of the reproduced data, and demodulates the data which has been modulated for recording. The data demodulated by reproduction demodulator 13 is delivered to error correction decoder 14, the error correction decoder 14 corrects the correctable error based on an error correction parity added at recording, and outputs DV bus data 15. The digital I/F 16 converts the DV bus data 15 into the 1394 Format digital signal to be outputted from terminal 17.
In the DV Format, video signals are compressed by the unit of each respective frame, so audio data are controlled also by the unit of each respective frame. There are two kinds of methods specified in the format for controlling the number of samples within a frame; lock mode and unlock mode. The lock mode is a mode in which the number of samples within frame is controlled fixed. In the 525/60 system 48 KHz sampling, for example, the number of samples in one unit of 5 frames are controlled fixed, the 5-frame sequence, whereas in the 625 scanning line/50 field" (hereinafter referred to as 625/50 system) signal, the number of samples may be controlled fixed by the unit of each 1 respective frame, so no sequence is taken. The unlock mode is a mode in which the number of samples in one frame may take any number within a certain range. Further, in the DV Format, there are two kinds of sampling methods, depending on the broadcasting system, in the preprocessing for the video signal compression. In the 525/60 system, the video signal sampling is based on the 4:2:2 component signal of ITU-R Rec. 601, the colour difference signal undergoes a 1/2 band width restricting process in the horizontal direction and is decimated in the horizontal direction by each 1 pixel (4:1:1 sampling); whereas in the 625/50 system, the video signal sampling is likewise based on the 4:2:2 component signal, and the colour difference signal undergoes a 1/2 band width restricting process in the vertical direction and is decimated in the vertical direction by each 1 pixel (line) (4:2:0 sampling).
DVCPRO (trademark applied) Format is being proposed as a DV Format for professional and broadcasting application. The DVCPRO Format is described in the Technical Report of The Institute of Electronics Information and Communication Engineers (Professional-use 1/4 inch Digital VCR Format DVCPRO", MR95-37, October 1995). In the DVCPRO Format for professional and broadcasting application, only the 48 KHz sampling lock mode is supported as the audio record format, and only the 4:1:1 sampling is supported as the video recording format.
However, when using the digital interface with a DVCPRO Format recording/reproducing apparatus, in which only the 48 KHz sampling lock mode is supported as the audio record format and only the 4:1:1 sampling is supported as the video record format, following drawbacks arise.
A first drawback is that an audio data sampled by other frequency such as 32 KHz, 44.1 KHz etc., or a 48 KHz unlock mode audio data can not be transmitted and recorded from a DV Format recording/reproducing apparatus via said digital interface.
A second drawback is that even between recording/reproducing apparatuses of the same DVCPRO Format an audio data can not be recorded with right sequence via said digital interface unless the audio data is locked at the 5-frame sequence at each of the respective recording/reproducing apparatuses.
A third drawback is that when reproducing a DV Format recording medium on a DVCPRO Format recording/reproducing apparatus an audio data other than 48 KHz sampling lock mode is outputted to said digital interface as the DVCPRO Format data.
A fourth drawback is that it is unable to transmit and record a 4:2:0 sampled video data from a recording/reproducing apparatus in which the data is recorded in DV Format via said digital interface.
A fifth drawback is that when reproducing a DV Format recording medium on a DVCPRO Format recording/reproducing apparatus a 4:2:0 sampled video data is outputted to said digital interface as the DVCPRO Format data.
Among the recording/reproducing apparatus such as digital VCR etc., the present invention enables, even in the cases in which different systems of audio sampling and video compression are used, to implement a recording apparatus which can record a data transmitted through the digital interface, a reproducing apparatus which can output a reproduced data through the digital interface, and a conversion apparatus which can convert and output a data transmitted through the digital interface.